Derivatives - Derivative Information about U.S. Treasury Futures (Details) - USD ($)	Mar. 31, 2025	Dec. 31, 2024
Derivative [Line Items]
Derivative assets	$ 6,791,000	$ 133,000
Margin Deposit Assets	258,700,000	219,200,000
Variation Margin Payable, Derivative	4,100,000
Variation Margin Receivable, Derivative		10,400,000
U.S. Treasury futures
Derivative [Line Items]
Derivative assets	0
Derivative liabilities	17,400,000
Fair Value		1,200,000
Interest rate swaps
Derivative [Line Items]
Derivative assets	0
Fair Value	$ 36,100,000	$ 152,800,000